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I know it's not the lens because the defect is obvious even when the lens is off.

It still fires up, and burns okay, seems to be about half as potent at burning, and beam is AWFUL
This is hard to describe (so bear with me), When I try to focus it to infinity, the middle section will come to a focus, but more than half of the outer part of the beam spreads out away from the dot.

Is the pic you posted showing the output of the raw diode without a lens? If so, the
problem might be as simple as crap on the window. If anything were to fall onto the
window during assembly, it would be baked on when the laser is powered up and cause
the ouput to look dirty.

You say you have a Laser Diode...
You don't say...
1) what it is mounted in
2) what is driving it and at what current
3) what lens you are using
4) what distance from the aperture the Laser Beam profile
is being looked at.... etc.

Do you have a pic with it in focus. I burnt one of my a140's using an acrylic lens and it left an aura around the dot when focused. I was hoping it was just the lens but changed out several with the same effect and ended up having to change out the diode. No aura now.

Did not try it but Daguin did suggest this for cleaning the diode

Quote:

Originally Posted by Daguin

Try lens cleaner and then PURE acetone. Be gentle and DO NOT use nail polish remover type acetone.

The problem is either on the diode window or with the laser diodes die,
could you take a pic of the diodes window, to see if it has anything baked on it,
or if the diode window is warped in anyway, skewing the ouput pattern

these doides all have a bit of thermal paste on them when they come out of the 'array'-- I put a piece of scotch tape over the windows is keep everything out as soon as I remove the array from the bottom of the C*sio--- they sell a small handheld microscope at RatShack for cheap-- it really lets you see what is there. I keep mine handy all the time. If you see anything on there that cannot be removed with a swab and a little high % alcohol may be time to move on to a new diode--

-I seriuosly doubt that Andrew got anything in your diode window--but if you got some on your fingers from the can it could have easily gotten there inadvertantly. hope this helps

I use 91% isopropyl alcohol ("rubbing alcohol) with a cotton swab. Make sure you have one that is tightly wound so you don't leave stray fibers and just dip the end of the swab in a little alcohol (you just want it damp, not dripping!) and VERY lightly touch the window and run it across. Let the alcohol evaporate, do not dry it. Then look at the window very closely under a lamp so you can use the reflection to look for any defects. If there is, then repeat as necessary.

If you push down, make a grinding motion (twirl it on the window), rub, push too hard, etc, you risk breaking or pushing the window in or scratching it. From that point, your only option is to de-can, which is not easy in comparison. Plus, you risk breaking the wires connecting to the die on the inside, which are extremely fine gold wires and not feasibly repairable.